This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of the study is to determine the role of arginase in reflex cutaneous vasodilation in a healthy aged human subject group (65-85 years old) compared to a healthy young subject group (18-30 years old) and to examine the relative role of reactive oxygen species on the NO-dependent portion of reflex cutaneous vasodilation in an aged humans subject group compared to a healthy young subject group.